The need to eat fresh green leaves has been there from the days of earliest man, and is especially acute at this time of year, when edible leaves of any kind are at their scarcest in the garden. The secret of having salad leaves in spring is to sow them in late summer and the new year, the first to overwinter and the second to provide an in-between harvest before the spring sowings become big enough to pick. Although there is a good range of leaves available in seed form - rocket, mizuna, mibuna, endives, dandelion, cress, spinach, chicory, sorrel, orache, purslane, claytonia, lamb's lettuce, mustard and beetroot tops, to name a few off the top of my head - it is lettuce that fulfils the proper role of a salad.
John Evelyn, writing in the late 17th century, argued that the best salads were comprised of three or four different types of salad and perhaps unblanched endive, succory (chicory) and purslane. He writes of different lettuces, such as 'a dwarf kind, the oak leaf, Roman, shell, and Silesian, hard and crimp (esteemed of the best and rarest) with divers more'. A salad was, at his table, a perfect blend of freshness and sophistication, just as I hope it is at mine.
But twas not always so. Somewhere along the line the English lost the art of the salad. When I was a child, lettuce was wheeled out in the same way cabbage, peas or tomatoes are now - often enough to be unremarkable, but as part of a dish which was ubiquitously known as 'salad'. Say 'salad' in 1966 - well, right up to 1996 in corners of Herefordshire - and everybody knew that it invariably included lettuce, hard-boiled egg, beetroot, radish and mayonnaise. A pork pie was never far away, or as like as not Spam. Sometimes one went abroad and came across a green salad that - laughably - only included lettuce. Nevertheless, salad, be it never so richly adorned, was the shortest of culinary short straws.
Quite a lot of my reluctance was due to the type of lettuce that was always used in our household in the Fifties and Sixties - the butterhead. Look at any photographs of walled vegetable gardens throughout most of the 20th century and you are sure to see a row of butterhead lettuce. These, Lactuca sativa var capitata, are the ones with rosettes of soft, cabbage-like leaves. They can be delicious, but they can also be limp, tasteless and infused with all the mournful boredom of a Sunday afternoon in East Cheam.
However, they do have the virtue of growing well in cold weather, so they can provide fresh leaves in winter, when one is generally less discriminatory about such things. And butterheads, such as a good 'Tom Thumb', sown in the New Year and grown with protection, can be harvested whole from late March through to May; they have a delicacy and freshness that is truly delicious. 'All the Year Round' is, as the name implies, hardy and adaptable enough to crop most of the year, and while not the best you can grow, it's a lot better than almost anything you can buy, especially in that spring gap when there is precious little else in the garden.
'Valdor' is another overwintering butterhead I grow, sowing the seeds in August for harvesting from Christmas-time onwards. Butterheads store badly, so they should be cut and eaten on the same day.
Better than a good butterhead is a moderate cos, L sativa var longifolia. Most cos lettuces do not grow well over winter, but 'Little Gem' will do well from an early sowing and certainly is always worth finding room for in the garden. It has been bastardised by its popularity, but it is a good lettuce and a home-grown one will astonish you with its freshness and taste, compared with the supermarket version - grown with all the artfulness that the desire for profit, speed and storage can devise.
'Lobjoits Green Cos' is a better cos, much bigger, rather slower to develop and with a shorter season, but probably the best lettuce that you can grow or eat. Although reputedly the slowest lettuce type to run to seed, I have often gone away for a couple of days leaving a bed of superb cos without a hint of bolting, only to come back and find the whole lot shooting up in an elongated attempt to set seed. Lettuce leaves are still edible when they have bolted, but they get very bitter. But none of this is a disaster. The chickens like them and they can be added to the compost heap. Just grow more.
'Rouge d'Hiver' is a cos that will grow in cooler conditions (although not really over winter) and 'Paris Island Cos' is another I grow and enjoy. 'Kendo' is good for early spring, with a bronzy blush to its leaves. You can get red cos, too, which adds variety, if not any extra taste. Cos lettuces not only taste better than most lettuces, they are also higher in vitamin C and betacarotene than the ubiquitous iceberg - a nasty, tasteless thing, and never worth giving garden room to.
Loose-leaf, or salad bowl, lettuce (L sativa var. crispa) is always useful, tasty and nutritious. It never matches the best of a good cos but it's invaluable. I grow red and green oak-leaf varieties (they come with various proprietary names), and 'Merveille de Quatre Saisons', a very good year-round lettuce. All can be picked leaf by leaf or cut flush with the ground and left to regrow for at least one, and usually two subsequent cuttings.
If you eat a lot of lettuce - and I reckon on eating some at least once a day, often twice - it is usually preferable to have a good steady supply of the types you like rather than a wide range of obscure varieties; that's entertaining for the horticulturist but makes less sense for the epicure. I'd suggest a good batch of no more than half-a-dozen lettuces at any one time from the scores available as packets of seed. Experiment until you find the ones you like and then concentrate on growing them well.
Lettuce germinate at surprisingly low temperatures; many will fail to germinate once the soil temperature rises above 25C - which you often get from mid-June to August. This can lead to a dearth of lettuce in August, as mature plants suddenly go to seed and there is a lack of young plants to replace them, because germination has been poor in the previous month. There are ways around this. Sow in the afternoon so that the vital germination phase coincides with the cool of night. Sow in seed trays and put them in the shade, and cover with glass or newspaper to keep them cool until the seedlings appear. And if the seeds are showing no signs of life after a week, put them in the fridge for 24 hours. In fact, late August- and September-sown lettuce do very well because the nights are getting cooler.
If you are sowing directly into the soil (something I never do nowadays, as slugs attack the very young seedlings in my garden), water the drill before sowing to cool the soil down. And make sure you sow into a shaded part of the garden.